object SetDemo {
 def main(args: Array[String]): Unit = {
   var members = Set("张三", "李四", "王五")

   members += "李四"
   members += "赵六"

   println("志愿者社团成员：")
   for (member <- members) {
     println("- " + member)
   }

   val hasZhangsan = members.contains("张三")
   println(s"是否有张三？$hasZhangsan")

   println(s"实际成员数：${members.size}")
 }
}
//11.1113【动手练习2】：用 Set 管理社团成员